The following compound Z is the most common intermediate used in the field of medical synthesis,

Wherein Y is a hydrogen atom or C1˜C6 alkyl.
M is a hydrogen atom or a protecting group on nitrogen.
X is a hydrogen atom or a protecting group of carboxyl.
Currently, there are a limited number of routes for preparing the above-mentioned compound, in which the yields are mostly low and the starting material is difficult to be produced.
When Y is a hydrogen atom, M is t-butyloxycarboryl (Boc), and X is methyl, compound Z has the following structure of formula Z-1,

The PCT patent application No. WO2009118759 disclosed a method for preparing compound Z-1, which can be summarized as follows:
                Wherein 9-BBN is abbreviation for 9-Borabicyclo[3.3.1]nonane, the yield is 46% in the first step, and it's 56% in the second step.        
When Y is a hydrogen atom, M is t-butyloxycarbonyl (Boc), and X is tert-butyl, the said compound is represented by the following formula:

The same route for preparing the above-mentioned compound was disclosed in both Bioorganic & Medicinal Chemistry Letters, 21, (12), 3771-3773, 2011 and PCT patent application No. WO2004039367, which can be summarized as follows:

The yield is 41% in Bioorganic & Medicinal Chemistry Letters, 21, (12), 3771-3773, 2011, and 27% in WO2004039367.
When Y is methyl, M is t-butyloxycarboryl and X is methyl, the said compound can be represented by formula Z-3. When Y is methyl, M is t-butyloxycarboryl (Boc) and X is a hydrogen atom, the compound has the structure of formula Z-4:

PCT patent application with publication No. WO 2012068234 disclosed the following method for preparing the two aforesaid compounds on page 876.

The above-mentioned methods are difficult to realize commercial production due to the use of high toxicity chemical such as 9-BBN, borane and sodium cyanide etc., and difficult operation processes. Therefore, it is necessary to provide novel methods to prepare the compound of formula Z.